Good pupillary dilation is beneficial for numerous medical procedures, such as, vitreoretinal surgery, anterior segment surgery, and phacoemulsification to name but a few. If an operation is performed through a small pupil, it can lead to severe trauma to the iris posterior pigment epithelium and damage to the iris sphincter resulting in permanent iris distortion and disabling glare. Additionally, poor visualization of the procedure may lead to small capsuleorhexis (which may result in a contraction syndrome requiring a subsequent lens explantation), zonar dehiscene, capsular rupture, vitreous loss leading to permanent decreased vision, lens material in the posterior segment requiring retinal surgery for removal, retained cortical material and prolonged surgical times. Each of these complications is potentially avoidable by fixed dilation of the pupil. Although mydriatic drugs are preferred for dilating the pupils, in many patients these drugs are ineffective because of the patient's ocular pathologic characteristics (i.e., aphakia, diabetes, phlogistic diseases, etc.). Several solutions, both demolitive and conservative, have been attempted.
The demolitive measures, such as irridectomies, sphincterotomies, and removal of the pupillary sphincter, for example, all suffer from the same shortcomings; each can potentially permanently deprive the patient of normal pupillary kinetics. For example, sphincterectomies may lead to permanent dilation and disabling glare, whereas preplaced sutures are tedious to place and may induce bleeding.
Among the conservative measures, pupillary stretching is most popular. However, this technique cannot be used on phakic eyes. Further, it is time consuming to implement and tends to stress the iris sphincter at individual points, thereby causing irregular distortions in the iris, sphincter tears, radial streaks of iris atrophy.
Thus, there has been a considerable need for a procedure for reliably and easily dilating the of a patient while at the same time protecting the iris from damage.